21,665 research outputs found
Prediction of Drilled Shafts Axial Capacities Using CPT Results
Results from nineteen full-scale axial load tests are reviewed to compare methods for predicting axial capacities of drilled shafts using results of Cone Penetration Tests (CPT). The three methods to estimate failure loads are: (1) Nottingham method, (2) Laboratoire des Ponts et Chaussees method (LPC), and (3) the Poulos and Davis method. Comparisons are made to assess the accuracy and dependability of each predictive method. Analyses of results indicate that the LPC method provides the most reliable predictions for axial capacities of drilled shafts in clay
The Reionization History in the Lognormal Model
We study the evolution of baryonic gas before the reionization in the
lognormal (LN) model of cosmic clustering. We show that the thermal history of
the universe around the reionization can roughly be divided into three epochs:
1) cold dark age , in which baryon gas is neutral, and opaque to
Ly photons; 2) hot dark age , in which a predominant
part of baryon gas is ionized and hot, but it is still opaque to Ly
photons; 3) bright age , in which the universe is ionized highly
enough to be transparent to Ly photons. In the flat cold dark matter
cosmological models given by WMAP and COBE, the difference of the two redshifts
is found to be as large as with and
. This reionization history naturally yields a high optical depth
to the CMB observed by the TE polarization of the
WMAP, and a low redshift of the appearance of the Ly
Gunn-Peterson trough in QSO's absorption spectra. The
reason why the universe stays long in an ionized, yet Ly opaque, stage
is because the first photo-ionization heats the intergalactic gas effectively
and has balanced the gravitational clustering a long period of time. Therefore,
the result of a high and low is a common feature of all the
models considered. Besides the cosmological parameters, the only free parameter
we used in the calculation is , the mean ionization photons produced
by each baryon in collapsed objects. We take it to be 40 - 80 in the
calculation.Comment: AAS Latex file, 29 pages, 6 figures included, accepted for
publication in Ap
Soft Color Enhancement of the Production of J/psi's by Neutrinos
We calculate the production of J/psi mesons by neutrino-nucleon collisions in
fixed target experiments. Soft color, often referred to as color evaporation
effects, enhance production cross sections due to the contribution of color
octet states. Though still small, J/\psi production may be observable in
present and future experiments like NuTeV and muon colliders.Comment: 7 pages, Revtex, 4 postscript figures, uses epsfig.st
Negative-Parity States and beta-decays in odd Ho and Dy Nuclei with A=151,153
We have investigated the negative-parity states and electromagnetic
transitions in Ho and Dy within the framework of the
interacting boson fermion model 2 (IBFM-2). Spin assignments for some states
with uncertain spin are made based on this calculation. Calculated excitation
energies, electromagnetic transitions and branching ratios are compared with
available experimental data and a good agreement is obtained. The model wave
functions have been used to study -decays from Ho to Dy isotones, and
the calculated values are close to the experimental data.Comment: 23 pages and 8 figures. accepted by Physical Review
On Forward J/\psi Production at Fermilab Tevatron
The D0 Collaboration has recently reported the measurement of J/\psi
production at low angle. We show here that the inclusion of color octet
contributions in any framework is able to reproduce this data.Comment: 1 page, Revtex, uses epsfig.sty, 2 postscript figure
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